The formation of aquatic adventitious roots (ARs) is considered an important adaptation to the adverse conditions of flooding. These roots replace the original root system, the growth of which is inhibited by oxygen deficiency in the flooded soil.
New ARs are supposed to increase fitness during flooding by improving nutrient uptake. However, they may also incur costs to the plant’s energy and carbohydrate budget. Zhang et al. show that the balance between the potential benefits and costs depends on the duration of partial flooding in Solanum dulcamara (Bittersweet). Net benefits were found in long-term but not in short-term flooding, indicating an adaptive role of ARs only during long-term flooding.